CE421/521

1
CE421/521

• Energy and Metabolism

2
Bioenergetics

• Thermodynamic considerations
• Thermodynamic relationships govern whether a
  reaction can occur
• Simply because a relationship is
  thermodynamically possible still may not occur
• Could be activation energy required
• Biochemical reactions require specific enzymes
• Genetic potential required for production of
  specific enzymes

3
Gibbs Free Energy
Where ?G is the change in Gibbs free energy ?H is
the change in enthalpy and ?S is the change in
entropy for a closed system at constant
pressure For a reaction to proceed, the entropy
of the system must increase, i.e., ?G must be
negative
4
Gibbs Free Energy (contd)
5
Gibbs Free Energy (contd)
6
Gibbs Free Energy (contd)
7
Gibbs Free Energy (contd)

• ?G for elements is zero
• Just because ?G is negative does not necessarily
  mean the reaction will proceed
• Relationship of ?G is valid for equilibrium
  conditions (says nothing about whether reaction
  will proceed)
• Thermodynamic equilibrium (nothing to say about
  rate of reaction kinetics)

8
Oxidation Reduction

• Another measure of the energy contained in a
  compound is its oxidation state
• Oxidation is the loss of electrons (often
  associated with dehydrogenation)
• Reduction is the gain of electrons (often
  associated with hydrogenation)
• The carbon in CH4 is completely reduced and has
  an oxidation state of -4
• The carbon in CO2 is completely oxidized

9
Oxidation reduction reactions

• In biochemical reactions there are electron
  d________ and electron a__________
• In general the electron donor is the energy
  source
• The electron acceptor is the last step in the
  electron transport system (ETS) the terminal
  electron acceptor

10
ThOD, COD, and BOD
11
Microbial Metabolism

• Enzymes
• p______ specific for a particular
  m_______________ (substrate)
• c______________ of biochemical reactions, but do
  not get consumed in the reaction
• c__________________ applications exist

12
Enzymes Contd

• some non-p_____________ molecules may be involved
  in enzyme catalyzed reactions
• co-factors or co-enzymes (e.g., nicotinamide
  adenine dinucleotide, NAD, NADH, also FAD, FADH)
• may also act as e____________ carriers

13
Enzymes

• Six categories of enzymes
• oxidoreductases involved in o____________
  reduction reactions
• transferases transfer of constituents from one
  c________________ to another
• hydrolases responsible for h___________ of
  carbohydrates, proteins, and lipids
• lyases catalyze the a____________ or removal of
  constituents
• isomerases i____________ formation
• ligases join m______________, p____________
  formation

14
Kinetics

• Enzyme Kinetics enzymes are catalysts in
  biodegradation and metabolism
• S E ? ES ? P E
• S substrate
• E enzyme
• ES enzyme substrate complex

15
Michaelis - Menton
16
Michaelis - Menton
17
Michaelis-Menton vs Monod
18
Lineaweaver-Burke Example
Calculate vmax and Km for the following data
V, mol/L min S, mol/L
0.00064 0.01
0.00058 0.008
0.000479 0.006
0.00038 0.004
0.000219 0.002
19
Lineaweaver-Burke Example
20
Microbial Growth Kinetics

• Procaryotic cells divide by b________ fission
  simple c_________ of DNA and cell division
• growth rate increase in n__________ of
  microorganisms or increase in microbial m___
• time required for microbial population to
  d__________ generation time (doubling time)
  during unlimited growth conditions
• b____________ versus continuous culture
• growth curve

21
Growth Curve
22
Growth Curve (log scale)

• stationary phase, g________ decay
• death phase how to distinguish bacterial
  d___________ versus bacterial d_________?

23
Continuous Culture

• m________ b______________ on substrate

24
(No Transcript)